Susan Phillips studies and writes about graffiti as an anthropologist. In 2000, while doing research for her book, Wallbangin’: Graffiti and Gangs in LA, she stumbled upon some graffiti that stunned her.

Under a century-old bridge near the Los Angeles River, Phillips discovered what appeared to be grease-pencil markings – a practically extinct type of American hieroglyphics called hobo graffiti.

The hobo graffiti was essentially very old examples of “so and so was here,” and dated back to 1914. Much of it was signed by hobos whose monikers have long been forgotten.

Source: Texas Public Radio